This invention relates to the application of coatings to filaments, and more particularly to systems and methods of applying a coating to a filament that forms a glass strand.
In the manufacture of textiles, including glass filament fabrics, it is a common practice to apply various coating solutions, e.g. sizes (also referred to as binders) and dyes to the surface of the advancing filaments as they are pulled from a bushing before being gathered into one or more strands. The sizing solution is applied to enhance or provide a given characteristic of or to the filament, such as improved tensile strength and abrasion resistance. Various methods and application devices may be utilized to apply the coating solution, such as a sprayer, pad, roll, or belt that transfers the solution from a reservoir to the filaments.
It is generally necessary to maintain a fresh supply of binder solution in the applicator in order to apply a suitable coating to the filaments. As such, an excess of binder solution may be supplied to the reservoir during operation and the excess solution is typically collected, returned to and recirculated by a binder circulation system. The excess binder collection device can be, for example, a weir, a vertically oriented tube disposed within the reservoir, a wall or channel having a given height into which the excess solution drains. However, the excess binder collection device can become clogged with dried solution, as a liquid-based portion of a non-circulating solution can dry upon exposure to air. Other applicator configurations use a float valve to control the amount of solution in the applicator. In particular, an indictor device floats on the surface of the solution and is connected to a supply system that will supply additional solution to the applicator when the level of the device gets too low. For more information concerning applicator configurations, see K. L. Loewenstein, The Manufacturing Technology of Glass Fibres, (Third Edition 1993) at pages 165-172, which is hereby incorporated by reference.
It is generally necessary to maintain a supply of solution having a known composition in the applicator reservoir, as the composition of the solution affects the final characteristics of the coated filament. However, due to openings to the reservoir in some systems, foreign matter can mix with the solution in the reservoir, thereby changing the composition of the solution and/or contaminating the solution. For example, in some systems, such as a glass filament production system, a liquid such as water is sprayed onto the hot filaments to cool them prior to applying the coating solution to the filaments. This cooling liquid can collect on the applicator housing and drip into the reservoir or onto the surface applying the solution to the filaments, thereby altering the known composition of the solution. Furthermore, openings in the applicator housing can allow other airborne contaminants, such as glass filaments or water droplets, to enter the housing and contaminate the solution. Additionally, these openings in the applicator housing can allow the high velocity air current associated with the passing filaments to circulate within the housing, thereby compounding the contamination problem by drawing in contaminants, and also serving to dry any non-circulating solution. Further, any contamination or dilution of the solution in the reservoir can contaminate or dilute the solution in other associated applicators if contaminated excess binder solution is collected and recirculated within a system of connected applicators.
Thus, embodiments of the present invention provide systems, methods and devices for applying an at least partial coating of a solution of a known composition to passing filaments, while eliminating the need to collect and recirculate excess binder solution, preventing binder from overflowing the applicator reservoir and becoming wasted and shielding the solution in the reservoir from contamination.
One aspect of the present invention is an applicator for applying at least a partial coating of a solution to a filament, comprising: an applicator surface operable to at least partially coat a filament with a solution; a first container operable to supply the solution to the applicator surface, a volume of the solution in the first container corresponding to a solution level in the first container; a second container operable to contain a supply of solution in fluid communication with the solution in the first container such that the solution in the second container has a solution level indicative of the solution level of the solution in the first container; and a detector for determining the solution level within the second container, the detector operable to control an adjustment of the volume of the solution in the first container such that the solution level in the first container is maintained within a predetermined range of levels. In one nonlimiting embodiment, the applicator further comprises shielding for covering the first container and directing excess external liquid on the shielding away from the solution in the first container, the shielding having an opening, wherein the applicator surface projects from the opening such that the filament is contactable with the applicator surface.
Another aspect of the present invention is an applicator for applying at least a partial coating of a solution to a filament, comprising: an applicator surface operable to at least partially coat a filament with a solution; a container operable to supply the solution to the applicator surface, a volume of the solution in the container corresponding to a solution level in the first container, the container further having an overflow level; shielding for covering the container and directing excess external liquid on the shielding away from the liquid in the container, the shielding having an opening, wherein the applicator surface projects from the opening such that the filament is contactable with the applicator surface; and a detector for determining the solution level within the container, the detector operable to control an adjustment of the volume of the solution in the container such that the solution level in the container is maintained within a predetermined range of levels which is below the overflow level.
Yet another aspect of the present invention is an applicator for applying at least a partial coating of a solution to a filament, comprising: a container operable to supply the solution, a volume of the solution in the container corresponding to a solution level in the container; an endless belt having an applicator surface operable to supply the solution to the filament, the endless belt rotatably supported by at least a first support and a second support, wherein the first support is at least partially positionable below the solution level and the second support is positionable adjacent to a contact area between the applicator surface and the filament, and wherein a portion of the endless belt that delivers the solution to the contact area forms a predetermined angle with respect to a horizontal axis that is predetermined angle is dependent upon a desired film thickness of the solution on the applicator surface; and adjusters to adjust the position of at least one of the first support or second support.
A further aspect of the present invention is a system for supplying and applying at least a partial coating of a solution to a filament, comprising: a main container operable to supply a solution; a local container in fluid communication with the main container for receiving the solution from the main container, a volume of the solution in the local container corresponding to a solution level in the local container; an applicator surface operable to receive the solution from the local container and apply an at least partial coating of the solution to the filament; an auxiliary container operable to contain a supply of solution in fluid communication with the solution in the local container such that the solution in the auxiliary container has a solution level indicative of the solution level of the solution in the local container; a flow controller positionable between the main container and the local container to control a flow of solution from the main container to the local container; and a detector for monitoring the solution level within the auxiliary container, wherein the detector is operable to generate a signal to the flow controller in response to the monitored solution level of the auxiliary container such that the solution level in the local container is maintained within a predetermined range of levels.
Another aspect of the present invention is a system for supplying and applying at least a partial coating of a solution to a filament, comprising: a main container operable to supply a solution; a local container in fluid communication with the main container for receiving the solution from the main container, a volume of the solution in the local container corresponding to a solution level in the local container, the local container having an overflow level; an applicator surface operable to receive the solution from the local container and apply an at least partial coating of the solution to the filament; shielding for covering the local container and directing excess external liquid on the shielding away from the solution in the local container, the shielding having an opening, wherein the applicator surface projects from the opening such that the filament is contactable with the applicator surface; a flow controller positionable between the main container and the local container to control the flow of solution from the main container to the local container; and a detector for monitoring the solution level within the local container, wherein the detector is operable to generate a signal in response to the monitored solution level to the flow controller such that the solution level in the local container is maintained within a predetermined range of levels, which is less below overflow level.
Still another aspect of the present invention is a method of supplying and applying at least a partial coating of a solution to a filament, comprising: storing a volume of a solution in a container having an inlet connected to a supply of the solution, the volume of the solution in the container being associated with a solution level in the container; coating at least a portion of an applicator within the container with the solution; contacting at least one filament with the applicator to at least partially coat the filament with the solution; monitoring the solution level within the container; generating a signal indicative of the monitored solution level; adjusting the solution level to a level within a predetermined range of levels based on the monitored solution level; and isolating the solution in the container from receiving any excess liquid accumulated on the container or any portion of the solution exceeding the overflow level. In one particular nonlimiting embodiment, the container is a first container and monitoring comprises positioning a second container proximate to the first container; interconnecting the first container with the second container such that solution can flow between the first and second containers and a solution level within the second container is indicative of a solution level within the first container, and monitoring the solution level of the solution in the second container, and adjusting comprises adjusting the solution level in the first container to a level within a predetermined range of levels based on the monitored solution level of the solution in the second container, wherein the predetermined range of levels is less than the overflow level.